Channel structure for coolant in motor

ABSTRACT

When an operation of a motor cannot be continued due to a large amount of heat generated when the motor is rotated at a high speed and under a high load, the motor is usually cooled by adopting a cooling structure using a coolant with a high cooling performance. It is, however, difficult to cast a casing with a complex channel, and the manufacturing costs are high. According to the present invention, through channels (15a, 15a) are formed along a central casing (10) of a motor casing consisting of a main central casing (10), a front end casing and a rear end casing (12, 14) when casting, and each through channel (15a, 15b) is communicated via communication holes (16a, 16b, 18a, 18b) drilled in the front end casing (12) and in the rear end casing (14), so that the whole of the casing can be fully cooled.

TECHNICAL FIELD

The present invention relates to a channel structure for a coolant in amotor, and is especially appropriate for cooling a small motor with ahigh power output and a high revolutional speed by a coolant.

BACKGROUND ART

A motor cooled by a coolant can generate about 1.5 to 2 times as muchpower as a motor cooled by air, although the two motors have the samesize, since the coolant has a high cooling ability. Furthermore, thecoolant-motor can reduce an increase of a temperature of each part ofthe motor, due to a heat generated by a continuous high load, a coreloss during a high revolutional speed, frictional loss of a bearing, andso on. Moreover, a channel for a coolant must be formed in a motor, andaccordingly, in the prior art, a channel is formed when a casing of amotor is cast, and then a portion to be covered is covered by a platemember.

Generally, a motor is attached to a machine by the front end of thecasing thereof, and accordingly, a coolant must be supplied from therear of the motor, returned to the rear again, and after this cycle isrepeated several times, the coolant must be returned to a tank from therear. Therefore, a communicational channel must be formed when castingthe casing so that those longitudinal channels are communicated with oneanother, and accordingly, the casting of the casing is very difficultwhen producing a casing with such a defect.

DISCLOSURE OF THE INVENTION

Accordingly, an object of the present invention is to provide a channelstructure for a coolant in which the casting of a casing is easy and thecost of the casting is low.

In view of the above-mentioned object, the present invention provides achannel structure for a coolant in a motor, a casing of which isconstructed by arranging a front end casing, a central casing, and arear end casing along a longitudinal direction, characterized in that aplurality of pairs of channels are formed along the longitudinaldirection through the central casing so that each pair is substantiallyequidistant in a circumferential direction of the central casing, anouter contour of the front end casing being a substantially polygonalcolumn, a channel hole having a circular section being formed along thelongitudinal direction at corners of the front end casing correspondingto each channel of the central casing, and another channel hole having acircular section being formed perpendicularly to an outer face of thefront end casing to be communicated with the channel hole, the anotherchannel hole being communicated with another channel hole at each of thecorners.

The casting of the central casing is easy since channels for a coolantare formed in the central casing only along a longitudinal directionthereof. It is easy to provide a hole having a circular section to thefront end casing at a position corresponding to a through channel formedin the central casing along the same longitudinal direction as thethrough channel by drilling, and to drill perpendicularly to an outerface of the front end casing of a substantially polygonal column so thata lateral hole communicated with the above-mentioned longitudinaldrilled hole can be easily drilled, and both lateral drilled holesprovided to adjacent outer side faces are communicated with each other.One through channel called a going channel, of each pair of throughchannels provided to the central casing, is communicated with onelongitudinal drilled hole communicated with one lateral drilled holecommunicated with the other lateral drilled hole, and therefore, iscommunicated with the other longitudinal drilled hole communicated withthe other through channel, called a return channel, provided to thecentral casing. Namely, the above-mentioned going channel and returnchannel are communicated with each other via the drilled holes providedat a corner portion of the front end casing. The front end casing mustbe cooled, since a motor is generally attached to an applied machine bythe front end casing. The front end casing can be sufficiently cooledsince the above-mentioned drilled holes for communication are providedat a plurality of corners of the front end casing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a front end casing of a motor;

FIG. 2 is a sectional view taken along the line II--II in FIG. 1;

FIG. 3 is a perspective view of a central casing of a motor; and

FIG. 4 is a perspective view showing channels of casings of a motoraccording to the present invention.

BEST MODE OF CARRYING OUT THE INVENTION

The present invention will be described in detail hereinafter accordingto the embodiment shown in the attached drawings. A motor is providedwith a casing divided into three parts, each being arranged along alongitudinal direction, that is, a central axis direction of the motor,as shown in FIG. 4. The three parts constructing the casing having asubstantial rectangular column contour are a long central casing 10 inthe middle position thereof, a front end casing 12 at the frontposition, and a rear end casing 14 at the rear position. The front endcasing is made from cast iron, and the central and rear end casings aremade from aluminum cast alloy.

FIG. 3 shows a perspective view of a central casing 10 having asubstantially rectangular column contour. A pair of through holes 15aand 15b for a flow of a coolant are formed t each corner portion of thecentral casing along the longitudinal direction, when casting, whereinone through hole 15a is a going channel for a coolant flowing toward thefront end casing 12, and the other 15b is a return channel for thecoolant flowing back toward the rear end casing 14. It is easy to castthe through holes 15a, 15b and a central hole 17 to house a stator and arotor therein, as they are all formed along one direction.

Now, referring to FIGS. 1 and 2, communicational channels are formed asmentioned below, which communicate the above-mentioned going channel 15awith the return channel 15b at four corner portions 22a, 22b, 22c, and22d of the front end casing 12, and which cool the front end casing 12.Longitudinal holes 16a and 16b are formed by drilling to a predetermineddepth at respective positions corresponding to the going channel 15a orthe return channel 15b of the central casing 10. The longitudinal hole16a communicates with a lateral hole 18a formed perpendicularly to anouter face 20b of the front end casing 12 by drilling, on the otherhand, the longitudinal hole 16b communicates with the other lateral hole18b formed perpendicularly to an outer face 20c by drilling. The twolateral holes 18a and 18b communicate orthogonally. The lateral holes18a and 18b are plugged by usual members 24 at openings thereof formedat faces 20b , 20c, so that a coolant flows from the going channel 15a,to the longitudinal hole 16a, to the lateral hole 18a, to the lateralhole 18b, to the longitudinal hole 16b, and to the return channel 15b.Longitudinal holes along the longitudinal direction of the casing andlateral holes orthogonal to the longitudinal holes are formed on therear end casing 14 by drilling, as shown by a streamline in FIG. 4,these holes communicate the going channel with the return channeladjacent to the going channel in the central casing 10, and thus all ofthe pairs of through channels 15a, 15b can be communicated. Accordingly,a coolant can flow along the arrowed path shown in FIG. 4, having oneinlet and one outlet, so that each portion of the casing can be cooled.Note, obviously the arrowed flow path is provided to avoid the holes 26shown in FIG. 1, to which bolts are inserted.

It will be apparent from the foregoing description that, according tothe present invention, all of the flow channel holes to be formed bycasting are through holes in only a longitudinal direction, and thus thecasting is easy, and the flow channel holes are easily formed in thefront end casing perpendicularly to each face thereof by drilling, sothat a coolant can flow and cool the front end casing. Accordingly,there can be provided a casing in which flow channels are easily formedand having a low cost.

We claim:
 1. A channel structure for a coolant in a motor casing forhousing a stator and a rotor therein which is constructed by arranging afront end casing, a central casing, and a rear end casing along alongitudinal direction, wherein the improvement comprises: a pluralityof pairs of channels formed along the longitudinal direction throughsaid central casing so that each pair is substantially equidistant in acircumferential direction of said central casing, an outer contour ofsaid front end casing being a substantially polygonal column, firstchannel holes having a circular section being formed along thelongitudinal direction at corners of said front end casing andcorresponding to each channel of said central casing, second channelholes having a circular section being formed perpendicularly to an outerface of said front end casing with each second channel holecommunicating with a first channel hole and with another second channelhole at each of said corners, and a plurality of holes provided in saidrear end casing which communicate one channel of each pair of channelsin said central casing with a channel of an adjacent pair of channels insaid central casing.